Description: (Applicant's Description) The DNA Sequencing and Analysis Core is now in its 4th year of highly successful operation. Initiated as a fledging operation after the inception of the CU Cancer Center, the Core has grown remarkably with now 112 user groups, of which most are Cancer Center members. In addition to performing DNA sequencing reactions, Core services include preparation of various DNA templates and assisting customers with all technical aspects of DNA sequencing and analysis. The Core also prepares high-density filter arrays using customer prepared libraries. In addition to service functions, Core personnel reported improvements in basic DNA sequencing chemistry that permit longer, more accurate read-lengths and improved mutation detection. To facilitate research efforts of the CU Hereditary Cancer Clinic, the Core now offers screening for the BRCA1/2 185delAG, 5382insC and 6174delT mutations. Especially as a consequence of the Genome Project, the demand for DNA sequencing will continue to expand significantly. During the next period of support, the Core intends to continue its state-of-the-art services to Cancer Center members. Research-based mutation/polymorphism screening is also likely to expand. Over the past 4 years samples sequenced have increased from 1501 to 9410 (526%) and charge back fees have increased from $43,095 to $187,136 (334%). Because of the large increase we have been able to reduce fees which has led to continued increases in core usage. The core has been used by members of 9 of the 10 Cancer Center programs. The core will move to the Fitzsimons campus with the Cancer Center during the next grant cycle.